NASA Cassini Significant Events for 12/11/2013 - 12/17/2013

Cassini is orbiting Saturn with a 31.9-day period in a plane inclined 51.3 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on Dec. 18 using one of the 34-meter diameter Deep Space Network (DSN) stations at Canberra, Australia. Except for the science instrument issues described in previous reports (for more information search the Cassini website for CAPS and USO), the spacecraft continues to be in an excellent state of health with all of its subsystems operating normally. Information on the present position of the Cassini spacecraft may be found on "Eyes on the Solar System" at

Cassini spent this week coasting slowly up (northward) towards apoapsis while flying through Saturn's magnetotail, which is the anti-sunward part of the teardrop-shaped magnetic envelope. All week, the spacecraft has been more than twice the distance from Saturn as is its largest moon Titan. The spacecraft's position relative to Saturn is illustrated here (though without the invisible magnetotail):

Today is the fifth day of the Magnetospheric and Plasma Science (MAPS) instruments' eight-day campaign to study Saturn's magnetotail. The Magnetometer (MAG), the Magnetospheric Imaging Instrument (MIMI), and the Radio and Plasma Wave Science instrument (RPWS) were prime for acquiring data.

Winter for Earth's northern hemisphere and winter in the southern parts of Saturn and Titan prompted Cassini's graphic artist to create a wintery image for the holidays:

Cassini science sessions and press conference were well attended at the American Geophysical Union's 46th annual fall meeting this week in San Francisco. Among the many published results were some important observations of the depth of Titan's lakes and their composition:

On six occasions this week the DSN supported Cassini with two-way digital communications for telemetry and command, and radiometric tracking for navigation. The 70-meter and 34-meter diameter stations in California and Australia participated.

Saturday, Dec. 14 (DOY 348)

The weeklong MAPS observations of Saturn's magnetotail wrapped up today. Next, the Radio Science team had the spacecraft turn its high-gain antenna toward Earth and proceed to skew its attitude slightly for an hour, in a pattern designed to allow the team to calibrate the antenna's boresight. This was accomplished by capturing for analysis the changes in signal strength seen in the X-band (8 GHz) and Ka-band (32 GHz) radio frequencies being received by the DSN.

The Cosmic Dust Analyzer (CDA) took advantage of its great distance from Saturn and carried out a twenty-hour observation of interstellar dust.

Sunday, Dec. 15 (DOY 349)

CDA collected and analyzed interstellar dust again for thirteen and one-quarter hours today, and then repeated the experiment on the following day for fifteen hours.

Monday, Dec. 16 (DOY 350)

The flight team sent the first set of Instrument Expanded Block (IEB) commands to Cassini for use when the ten-week S82 command sequence begins execution. The S81 sequence will end, and S82 will begin, on Dec. 27. Following a round-trip light time of 2 hours 57 minutes, telemetry showed that all 7,054 individual commands were received intact and stored aboard. In between the IEB command files, the team sent up, and confirmed, a file of 139 freshly created commands for performing Orbit Trim Maneuver (OTM) 366. They were timed to execute on the following day.

The jet streams that make up the huge, curious hexagonal feature surrounding Saturn's north pole were the subject of an image featured today:

Cassini reached apoapsis at a height of 2.7 million kilometers from Saturn, having slowed to 10,509 kilometers per hour relative to the planet. The OTM-366 commands took effect and turned the spacecraft to the prescribed attitude and fired its main rocket engine for 2.14 seconds. This propulsive maneuver provided a change in velocity of 372 millimeters per second, adjusting the spacecraft's course slightly to set up for the next Titan flyby, T-97 on New Year's Day 2014.

Visit the JPL Cassini home page for more information about the Cassini Project: